thompson



(No Model.) I

W. G. THOMPSON.

' 4 LOOK. H N0.Z61,789. PatentedJuly 25,1882.-

fnesses lnz/enior pressure is brought against the NIT-ED STATES WILLIAM (J. T'Ho Pso ,-oF- MINNEAPOLIS, MINNESOTA.

LOCK.

SPECIFICATION forming part of Letters Patent N6. 261,789, datedJ'uly 25, 1882.

Application filed October 19, 1881. (No model.) I

To all whom it may concern Be it known that I, WILLIAM CASPER THOMPSON, a citizen of the United'States,re siding at Minneapolis, in the county 0; Hennepin and State of Minnesota, have invented a new and useful Improvement in Locks, of which the following is a specification.

The well-known Yale lock has been considered safe and secure; butI haze discov ered' that it can be very easily picked by inserting the short end of an L-shaped-wireinto the key-hole, it being made flat, so as to fit the hole tight and turn the cylinder. turning the cylinder with the wire a gentle sides of the tumblers, when those thatareheld fast are prized up with a small wire with a. curved end. There being a steady pressure on the side of the tumbler when it is raised so the upper part passes out of the cylinder, a slight forward movement is felt in the larger wire. The cylinder will then have turned enough to retain the upper part of the tumbler above it and prevent the lower part from being raised farther with the same force used before. The tumbler remains thus unlocked,and the others are manipulated in like manner until all are unlocked, when the wire turns the cylinder and withdraws the bolt. I

The object of my invention is to prevent locks being picked, as described above, or being opened by any means except with their proper keys. J 4 The invention consists of a cylinder or Yale lock, the cylinder of which is made in two parts, the front portion of which is furnished with a safety-tumbler.

The drawings and following description will fully explain the working of my invention.

Figure l is a plan showing front of lock. Fig. 2 is a sectional view, and Fig. 3 is a plan of key.

A is the front part of the cylinder; B, the rear portion, into which work the locking tumblers fff, and is separate from and inde pendeut of the part A.

G is the key-hole, passing through both parts of the cylinder. The part A of the cylinder being of larger diameter, the key-hole is not cut through to the outersurface, as it is tween the two tumbler is passed up into E is anadjusting-screw, with its center'exwhich preposition in part B, as shown in Fig. 1, the dotted line representing the diameter of the rear part of cylinder.

D is a safety-tumbler consisting of two pieces with a spiral spring beneath, inserted in a hole drilled through the body of the lock and into the cylinder part A. The upper partof thetumbler equals in length thedepth of the hole in the part A, so the with the outer surface of the cylinder, allowing it to be freely turned when the tumbler place by the spiral spring.

tended inside the spiral spring, vents the safety-tumbler being depressed farther than the bottom of the key-hole. Thus the cylinder part A is always looked when the safety-tumbler is pushed down.

G, Fig. 3, is the notch cut in the key, which the safety-tumbler rises when the is inserted in the lock 7 To operate the lock the key is inserted at an angle of forty-five degrees until it euters above and is then raised ona horizontal line and passed through. the key-hole. The safety-tumbler rises again as the notch it, and the cylinder is free to turn.

key

inder cannot be turned and bind the turn- PATENT OFFICE.

division heparts comes-on a. line 6 o I into depresses the safety-tumbler. It 7 in'thekey comes over q blers, as heretofore described. To prevent its 1 being turned I make the independent of each other.

cylinder in two parts To prevent anything being inserted in the key-hole and again joining the cylinder, parts, I furnish the part A with the safety-tumbler D, swers the purpose sought. 7

The part A of the cylinder furnished with the sa-t'ety-tumbler'can also be used in combinationwith other locks of difterent devices which use a flalhkey.

by suitable device. (Not shown in the drawings.) X

What 1 claim is- 1..The combination or cylinder with a safety'tumbleradapted to',

which fully anclose a portion of the key-hole and leave the The part is held in 1 of a. divided key hub 2 elaso.

front part of the cylinder unlocked when-at ,rest, but looking said part of -the'cylinder when pressed back into its recess, substantially as described.

2. The combination of a divided key hub or cylinder and safety-tumbler with a flat or sheet-metal key provided -with a notch to allow the safety-tumbler to return to its former positionafter hein g depressed by the insertion of the key, substantially asset forth, and for 10 the purpose described.

WILLIAM CASPER THOMPSON.

Witnesses:

JOHN A. LUCY, DELLA. MCORAGKEN. 

